Research towards a wake-vortex advisory system for optimal aircraft spacing

Gerz, Thomas; Holzäpfel, Frank; Bryant, W. H.; Köpp, F.; Frech, Michael; Tafferner, Arnold; Winckelmans, Grégoire

doi:10.1016/j.crhy.2005.06.002

Cited by 77 publications

(76 citation statements)

References 49 publications

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“…The Winckelmans (Gerz et al 2005) model and the Proctor (1998) model are two closely related empirical vortex models that include extra parameters to better match the contour-averaged data.…”

Section: Empirical Vortex Model Parameter Estimationmentioning

confidence: 99%

Flow field measurement around vortex cavitation

2015

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stage. These involve the smooth transport of vapor into the tip vortex, leading harmful implosions away from the propeller surface. The tip vortex cavity dynamics are not directly related to the propeller rotation rate. The excitation of this cavity often leads to high amplitude broadband pressure fluctuations between the fourth and seventh blade rate frequency (Wijngaarden et al. 2005).To better understand the sound production from vortex cavitation, a model for the waves on a tip vortex cavity was developed and was shown to be able to describe the interface dynamics in detail (Pennings et al. 2015). As a result, a condition could be predicted where a cavity resonance frequency could be amplified to produce high amplitude sound, as reported by Maines and Arndt (1997).The part that remains to be validated is a vortex model for the cavity size and cavity angular velocity. It has been shown that a Lamb-Oseen vortex model poorly estimates the cavity size as a function of cavitation number (Pennings et al. 2015). It is possible that overestimation of the vortex peak azimuthal velocity could have led to an overestimation of the cavity size. The main goal of the present study was to configure a simple low-order vortex model, to serve as an input into a vortex cavity wave dynamics model, to describe the tip vortex resonance frequency. It is based on the following steps.1. Model the tip vortex velocity field without cavitation (further referred to as wetted vortex) 2. Model the cavity size as a function of cavitation number based on wetted vortex properties 3. Show the difference in velocity field around a wetted and cavitating vortex 4. Obtain the cavity angular velocity value that gives the best correlation to the tip vortex cavity resonance frequency Abstract Models for the center frequency of cavitatingvortex induced pressure-fluctuations, in a flow around propellers, require knowledge of the vortex strength and vapor cavity size. For this purpose, stereoscopic particle image velocimetry (PIV) measurements were taken downstream of a fixed half-wing model. A high spatial resolution is required and was obtained via correlation averaging. This reduces the interrogation area size by a factor of 2-8, with respect to conventional PIV measurements. Vortex wandering was accounted for by selecting PIV images for a given vortex position, yielding sufficient data to obtain statistically converged and accurate results, both with and without a vapor-filled vortex core. Based on these results, the loworder Proctor model was applied to describe the tip vortex velocity outside the viscous core, and the cavity size as a function of cavitation number. The flow field around the vortex cavity shows, in comparison with a flow field without cavitation, a region of retarded flow. This layer around the cavity interface is similar to the viscous core of a vortex without cavitation.

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Section: Empirical Vortex Model Parameter Estimationmentioning

confidence: 99%

Flow field measurement around vortex cavitation

2015

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“…There are multiple quantities that influence the lifetime and trajectory path of wake vortices, such as ambient wind, turbulence, wind shear and turbulence stratification (Gerz et al 2005). Besides these quantities, near the ground, wake vortices can separate and rebound, leading to their decay (Robins and Delisit 1993).…”

Section: Wake Vorticesmentioning

confidence: 99%

“…Various studies (e.g. Harris et al 2002;Gerz et al 2005;Holzäpfel and Steen 2007) focus on Doppler lidar measurements to detect wake vortices. However, Doppler lidars have problems with retrieving the correct wind speed and wind direction near the surface.…”

Section: Introductionmentioning

confidence: 99%

Runway Wake Vortex, Crosswind, and Visibility Detection with a Scintillometer at Schiphol Airport

Dinther

Hartogensis

Holtslag

2015

Boundary-Layer Meteorol

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We evaluate the performance and investigate the capability of a scintillometer to detect wake vortices, crosswind and visibility near an airport runway. An experiment is carried out at Schiphol airport (Amsterdam, The Netherlands), where an optical scintillometer is positioned alongside a runway. An algorithm is developed to detect wake vortices, and also the strength of the wake vortex, from the variance in the scintillation signal. The algorithm shows promising results in detecting wake vortices and their strengths during the night. During the day, the scintillometer signal is dominated by environmental turbulence and wake vortices are no longer detectable. The crosswind measured by the scintillometer is compared with wind-speed and wind-direction data at the airport. Our results show that, after applying an outlier filter, the scintillometer is able to measure the crosswind over the short time period of 3 s required for aviation applications. The outlier filter does not compromise the capability of the scintillometer to obtain the maximum 3 s crosswind over a 10-min time frame correctly. Finally, a transmission method is used to obtain the visibility from the scintillometer signal, which is then compared with that obtained from a visibility sensor. The scintillometer is able to identify periods of low visibility correctly, although it shows a high amount of scatter around the exact visibility value.

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“…The St. Louis Lambert International Airport has been the primary test site for the current joint FAA-NASA wake turbulence program since 2003, [4][5] and the final configuration consisted of three SODARs spaced in an array parallel to one of the two arrays of crosswind propeller anemometers (otherwise known as a Windline, which tracks the vortex induced crosswinds), as well as along the scan plane of a WindTracer ® pulsed LIDAR (Light Detection and Ranging, essentially a RADAR operating in optical frequencies, manufactured by Coherent Technologies Inc, -Currently Lockheed Martin Coherent Technologies), and located to best measure the wakes from arriving aircraft on runway 12R. As the wakes transport laterally, the SODAR array measured the disturbance and quantified the decay from the first SODAR as compared to the second and third SODARs.…”

Section: A Sodar Placement and Data Quantitymentioning

confidence: 99%

Use of a Commercial Wind SODAR for Measuring Wake Vortices

Mackey

Burnham

2006

12th AIAA/CEAS Aeroacoustics Conference (27th AIAA Aeroacoustics Conference)

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This paper describes the application of a commercial wind SODAR (SOnic Detection And Ranging) to the measurement of aircraft wake vortices. Changes in data collection and processing were required to extract vortex location and circulation from the acoustic returns. Sample data are presented, and it is demonstrated that SODARs represent valuable addition to the existing array of sensors for tracking and characterizing aircraft vortices inground effect.

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Research towards a wake-vortex advisory system for optimal aircraft spacing

Cited by 77 publications

References 49 publications

Flow field measurement around vortex cavitation

Flow field measurement around vortex cavitation

Runway Wake Vortex, Crosswind, and Visibility Detection with a Scintillometer at Schiphol Airport

Use of a Commercial Wind SODAR for Measuring Wake Vortices

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